It will be fired out of a 22" barrel. I have some w748 on hand and have had good results with it pushing these same 40 grain pills out of my 223. I also have some varget on hand but I have read multiple places that muzzle velocity suffered somewhat when using varget in a 22-250 versus other powders. I can't confirm or deny this because I don't have a chronograph.
Peetza the velocities you are seeing are very nice. I would be quite pleased to see 4000 with the 40 grain vmax. I will have to look into it.

I have a few different reloading manuals but it is cost prohibitive and time intensive to buy a pound of each powder to find out whether it works or not. Granted, eventually you have a nice selection of powder to choose from for other projects but I would prefer to narrow it down based on what other people have tried first.